The ad is a tear jerker. If you haven't seen it, I suggest you watch it. The campaign conducted by the Canadian Heart and Stroke Foundation was not only designed to highlight the difficulties of end-of-life care, but also give a wake-up call to families. With easy access to junk food, and an electronic age encouraging children to play "Angry Birds" on their iPhone, rather than experience the real thing outdoors, there has been a major focus on cardiovascular health lately. While a balanced diet and exercise are the two most common methods of prevention, every effort been made to identify ways to improve vascular function with the hopes of preventing heart disease and improving end of life care. What if I told you laughing can contribute to just that?
Dr Sugawara and his team from The National Institute of Advanced Industrial Science and Technology in Japan investigated the effects of "mirthful laughter on vascular function", with a focus on arterial response.
Translation: They wanted to test how readily our arteries allow blood flow to the heart when we laugh.
To do this, the researchers focused on "arterial compliance" and "flow mediated dilation (FMD)". Arterial compliance is an indicator of how easily blood travels through our body. The stiffer (or less compliant) our arteries, the harder our heart has to work to contract. It is measured by comparing arterial volume and blood pressure. Ideally, compliant arteries show large changes of volume with variations in pressure. FMD on the other hand, is a non-invasive method of examining endothelial function, which is shown to be related to cardiovascular health. Low levels of FMD correlate with high blood pressure, an early indicator of heart disease.
So how did the researchers conduct their test? Using jokes of course! A set of "reasonably healthy" participants agreed to watch a comedy program of their choice (personally I would watch Will Ferrell's 'Step Brothers'), while others watched a documentary. Blood and pulse pressure readings were recorded, while arterial diameter and FMD were measured using ultrasound. The number of laughs was counted based on irregularities in breathing patterns, and was much greater during a comedy (97) than a documentary (5). Surprisingly, there was significant increase in arterial compliance during comedy films that matched an increase in FMD as well. To ensure these results were not simply due to mood changes, participants were required to fill out a survey following the end of the experiment. This quick test indicated no significant improvements in mood, despite their laughter. The researchers were able to conclude that the act of laughter itself was associated with increased vascular function.
What is it about laughter that can physically affect how blood travels through our bodies? Well, there are multiple hypotheses, but it turns out they all center around a chemical called nitric oxide (NO). NO has many effects on the body, but we will focus on its effects on the smooth muscle surrounding our blood vessels. Endothelium lines the inside of our blood vessels and controls our blood pressure by producing NO, which leads to smooth muscle contraction and dilation. Smooth muscle activity controls arterial diameter, and is therefore linked to vessel relaxation (aka compliance!). As you can see, the production of NO by our blood vessels plays a huge role in our vascular systems ability to efficiently transport blood through the body.
Just like other compounds in the body, NO levels have to be meticulously maintained. NO is also a neurotransmitter, so too much of it in our bodies can be a bad thing. Fortunately, our bodies have the incredible ability to balance these levels, and can promote excess NO production when it is healthy to do so. This is done through a series of mechanisms, one of which is suspected to be linked to laughter, and may account for the results seen in Sugawara's tests: Shear Stress.
Figure 1 - Diagram of blood vessel. The force of shear stress runs parallel to blood flow and induces nitric oxide production, which results in smooth muscle relaxation and vasodilation.
Shear Stress is the force of blood flow tangential to the endothelium and our blood vessels are subject to it all the time, especially when we laugh. Think about last time you saw someone laugh uncontrollably. A strong bout of laughter often results in shortness of breath, irregular body movements and overall chest muscle exertion. All this action is bound to increase heart rate, and therefore the shear stress of blood flowing through our arteries. The result? NO production! Shear Stress induces calcium production in the endothelium, which activates nitric oxide synthase (NOS). This enzyme converts L-arginine (an abundant amino acid in our cells) to NO in what is known as "flow-dependent formation". The gas rapidly diffuses away from the endothelium to the smooth muscle, where it has an attraction to another enzyme known as guanylyl cyclase. This enzyme catalyzes the synthesis of cGMP, a secondary messenger that induces smooth muscle relaxation via multiple mechanisms. For example, cGMP can inhibit smooth muscle contraction by lowering intracellular calcium concentration. Calcium plays a role in activating myosin light chains, the polypeptide structures that initiate constriction. In sum:
More NO = Less Ca2+ = Less constriction = Smooth Muscle relaxation = Increased Arterial Compliance
Figure 2: Shear stress induced NO signalling pathway producing cGMP
But now that we've speculated on the signalling pathways behind laughter's effects on vascular function, the question must be asked: how powerful are its long-term effects? It turns out arterial compliance and FMD increased by around 10% in individuals watching comedies, though the effects only lasted 30 minutes. Exercise on the other hand can increase arterial compliance by close to 50% in elderly populations, while a low-salt diet can increase long-term FMD by at least 2%. Laughing cannot replicate the intensity and duration diet and exercise provide those wishing to avoid cardiovascular disease.
However, there is no doubt that laughing does indeed positively affect our vascular health, and for that reason, I think it can be effectively implemented into the care of those we love. It is well-documented that arteries stiffen with age, leading to atherosclerosis. With so many elderly patients losing arterial compliance, laughing may be a remedy to, at the very least, help slow the deterioration.
In closing, as someone who has personally seen the ugly scenes shown in the above commercial, I cannot help but feel that every effort should be made to improve the final days of those in geriatric care. If laughter not only boosts one's mood, but their immediate health as well, I see no reason to not jump on that opportunity. A daily dose of laughter is not just good for the mind and soul, it is good for our heart too. If that isn't enough reason to implement laughter into healthcare, and turn that frown upside down, I don't know what is!
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